Dysfunctional Prone Hip Extension Functional Movement Test

Anatomy and Biomechanics:

This prone lying test assesses the recruitment of the gluteus maximus and hamstrings and requires 5 to 10 degrees of active hip extension mobility. Restriction of hip extension ROM can be due to tight hip flexors and/or a tight anterior hip capsule which needs to be addressed first before attempting retraining. (See Module #3) If the prone hip extension test is dysfunctional then to maximize gluteus maximus recruitment, retraining should initially begin with the hip flexed, ie,. short of neutral, thereby reducing some inhibitory factors.

Substitution patterns to watch out for during retraining:

Janda, 1990, originally described an ideal hip extension firing pattern in which the hamstrings fired first followed by the gluteus maximus then the contralateral and finally ipsilateral lumbar erector spinae. Subsequent studies have not supported this firing pattern (Pierce and Lee, 1990; Vogt and Banzer, 1997). Clinically what seems to be most important is whether or not the gluteus maximus fires at all and how well is the pelvis and trunk stabilized during hip extension. Often patients are able to extend a leg without any palpable tension felt in the gluteus maximus at all with substitution occurring by the patient using their erector spinae and hamstrings to lift the leg.

Patients will often substitute for a lack of hip extension mobility by anteriorly rotating the ipsilateral innominate as they raise the leg. This is why it’s important both during the functional movement test and during retraining that the therapist monitors the position of the PSISs during hip extension to insure that minimal anterior innominate rotation occurs (slight superior migration of the PSIS is ok).

The therapist should also watch for any pelvic rotation in the transverse plane during hip extension retraining indicative of a loss of anterior stabilization of the pelvis. This substitution pattern occurs due to inhibition of the abdominal obliques and hypertonicity of the erector spinae on one side, ie., during L hip extension the R ASIS lifts off the table excessively as the thoracolumbar junction and pelvis rotate to the R. These patients often present with an increase in tone and palpable tension of the R erector spinae muscles even with the patient lying at rest.